On the rare times I go out to eat (birthdays, mainly) I KNOW to order something I REALLY like because I’ll be eating it for two more meals as well.
Portion sizes these days are ridiculous.
There's some non-intuitive economics going on here.
The biggest driver of restaurant meal prices isn't the ingredients, it's the cost of maintaining the building (paying rent), utilities, preparing the food, serving it to you, and cleaning up after. If they cut the portion in half, it will still cost almost as much to prepare it and put it on your table. Apparently, a critical mass of customers get upset if the portion is "too small" relative to the price. So ... they give you a huge portion. And they don't get upset if you take half of it home for lunch.